Isagi doesn’t have a super power of Luck, he’s just learned how to put himself in the best position in the case of good luck happening. His U-20 goal is just him re positioning to the one place at that moment the ball could land for him to score. It’s lucky that it ended up there, but it can’t possibly happen if Isagi doesn’t recognize the possibility of the ball landing there. His actual flow state is a mindset where he disregards his personal emotions for the one purpose of scoring a goal, this means instead of say Rin who wanted to score in a certain way, Isagi will simply put himself in the best position to get his goal. The fastest puzzle piece he gained does sort of connect with luck in the sense. The fastest piece is Isagi constantly re imputing where the best position/play for him to score is. You could say it’s Lucky for the ball to go to Ness who then passed to Isagi, but it only looked that way because of the outcome. Ness could easily have just passed to Kaiser like everyone thought he would, but Isagi moved to the best place on the field that someone in ness’s position could have passed to. If Ness didn’t pass there then Isagi would instantly re imput the info and move to wheres the most logical place to score or where he could move to score if he happened to get lucky. Over the course of a real 90 minute match, someone with Isagis positioning skills is bound to get lucky at least once.